wrong calculation in line item subtotal, discount field in Quotes module version 7.2.2.0

My sugarcrm version is 7.2.2.0 and have professional edition.My Grand total section calculation is correct. when I create new quote , displaying correct calculation in line item (group) subtotal and discount , but when I edit line item then line item calculation gets wrong, It displays previously edited edited value calculation.Please help me to solve this..